Green Walls, Green Kidneys, Green Lungs

By Lione Clare

In two left footed boots, I squelched with the group through the clayey light brown mud to a plot within a two-hectare area of newly planted young mangrove trees. We were here to get our hands dirty, and that we did! In pairs, we planted around 40 young trees to help with the restoration effort at Can Gio Biosphere Reserve, home to the “most diverse and luxurious mangroves in the world,” according to one of our lecturers, Dr. Le Duc Tuan.

During the Vietnam War (in Vietnam they call it the American War), about one million gallons of harmful chemicals were sprayed over Can Gio Reserve to clear war zone lands. Over half the chemicals sprayed were Agent Orange, which completely destroyed 20,000 hectares of mangrove ecosystems in this area. Today, land use in these coastal areas favors more intensive agriculture, like shrimp aquaculture, which has led to continued clearing of mangrove forests. In Can Gio Reserve, however, farming and resource use is regulated and the 4,721-hectare “core zone” does not allow human activity; its sole purpose is to preserve the landscape and biodiversity.

Mangrove restoration in Can Gio Reserve, which began shortly after the War’s end in 1975, has resulted in a significant increase in biodiversity. Nearly 700 species, including catfish, crocodiles, otters, monkeys, shellfish, and invertebrates, now thrive within Can Gio’s mangrove forests.

Mangrove ecosystems are of great importance to the coastal zones of Vietnam. They not only provide for rich biodiversity and food sources, but also create a buffer for storms and prevent erosion during floods. Hence, they are also known as a “green wall.” Upriver, dams pose a threat to mangrove forests because they trap sediment, which mangroves need for anchoring root systems. That could mean bad news if a flood comes through. Additionally, mangroves play the role of “green kidneys” because the roots filter out pollution from Ho Chi Minh City and upriver industrial zones.

Climate change is projected to bring more intense storms and sea level rise, which will result in more erosion, flooding, and salinity in Vietnam’s coastal and low-lying regions, impacting people, infrastructure, and agriculture.

After planting the mangroves, we took skiffs along a river and through a mangrove corridor to a shrimp farm. We toured the farm and had a lovely meal of catfish, vegetables, rice, and oysters, which the farmer also harvests, all from the surrounding land. This year, the farmer noticed that the rains were different, continuing later than normal. This caused extended flooding and salt-water intrusion, thus high salinity content in the river. Dr. Ngan told us that baby oysters had difficulty surviving in these abnormally saltier conditions.

It is clear that when the projected effects of climate change occur, specifically sea level rise, survival of oysters and other food sources within the mangrove forests could be threatened. The farmer and his family we visited live almost entirely off the land; they only buy some rice and veggies during the dry season. If climate change effects result in insecure food sources, the livelihoods of Vietnamese relying on mangrove ecosystems for survival will surely be severely impacted.

Can Gio Reserve is known as the “green lung” for Ho Chi Minh City, because the wind is thought to bring oxygen generated from the forest. I think mangrove forests can also be thought of as a lung, or other vital function, for the whole planet because of their ability to sequester large amounts of carbon and produce diverse, productive ecosystems. Just like a mammal cannot breathe without lungs, the planet cannot breathe or function properly without its forests.

Clearly, it is increasingly important for mangrove forests to be preserved, because they both have intrinsic value to ecosystem function and protect people and the land from climate change impacts.

Squelching back through the mud, I realized that while I only played a small role in such an important effort, it was a rewarding experience nonetheless. The physical, real contribution of replenishing the green walls, kidneys and lungs of Can Gio Reserve allowed me to form a special connection with a place vital to climate change responses and be able to share this story.